Type-A monoamine oxidase

By Joseph Knoll

Type-A monoamine oxidase (MAO-A) is the form of monoamine oxidase (MAO) that is sensitive to clorgyline. Clorgyline, 3-(2, 4-dichlorophenoxy)-N-methyl-N-2-ynylpropan-1-amine, is an irreversible MAO inhibitor substance, structurally related to pargyline. This term was coined and introduced, in 1968, by Johnston, to distinguish between clorgyline-sensitive and insensitive forms of monoamine oxidase (MAO) enzymes that,he referred to as Type-A monoamine oxidase and Type-B monoamine oxidase, respectively. MAO-A was found to be present in the neurons, astroglia, gastrointestinal tract, liver and placenta (Neff and Gorodis 1972). By the early 1970, it was recognized that MAO-A is primarily responsible for the oxidative deamination of the monoamines serotonin, melatonin, noradrenaline (norepinephrine) and adrenaline (epinephrine), and not only of serotonin, as originally preoposed (Costa and Sandler 1972).